1. Field of the Invention
This invention relates to apparatus for applying a line of perforations of controlled length to sheets of paper while they are travelling through a paper folding or other machine.
2. Description of the Prior Art
The application of a line or lines of perforation to a sheet or sheets of paper to enable a portion of the sheet to be detached at a later time is not new.
Many advertising or mailer pieces are multi-part, in that a portion of the piece can be detached and returned to the sender for a variety of purposes, such as placing an order for a product, or obtaining a catalog, responding to a survey, or other uses.
It is not always convenient to produce a return piece of a mailing by using one straight line of perforations, and often two 90.degree. intersecting lines of perforations are needed to provide a detachable postcard sized return piece.
In order to put the intersecting lines of perforations on the mailer one common practice is to use a letter press and die which require additional labor and machine cost. Another approach is to paste a strip onto a printing roller blanket as backup for the die, but the resulting operation ruins the blanket and consequently increases the cost.
Another approach is to put in a perforation apparatus before the number I fold roller which includes a bottom roller and a perforation wheel which is brought down onto the paper sheet to be perforated.
The apparatus of the invention replaces the first set of fold rollers and selectively applies a line of perforations to a mailing piece while it is in a folding or paper processing machine, with control of the location and length of the line, so that a return mailer piece is available which can be easily detached and mailed back to the sender.
The apparatus of the invention also performs the feeding operation previously accomplished by the first set of fold rollers in the machine, which makes it useful for both old and new machines.
Various prior art structures have been proposed which perform operations such as detecting, slitting, and perforating sheets of material, but none of them perform the same as the apparatus of the invention.
The U.S. Pat. No. 3,076,365 to Taylor et al discloses a machine for slitting tissues, particularly tissues to be used as sutures, and cut from the intestines of beef, calves, sheep or swine. This apparatus is designed to be operated with wet material presented through a narrow tissue feed throat, and is not suitable for use with dry paper sheets. While the patent discloses a detection system for disclosing the presence of a strip to be split it lacks supporting rollers, is not suitable for applying perforated lines to sheets of paper, lacks the female collar with a groove below the perforation wheel, which is necessary for applying perforated lines.
The U.S. Pat. No. 3,165,019 to R. L. Graveley, Jr. discloses a re-indexing punching unit for making holes in moving strip stock, such as aluminum siding. No sheet detection system is disclosed, no rollers similar to applicant, and no adjustment whereby perforation lines can be placed on sheets of paper of selected length and at any desired transverse location.
The U.S. Pat. No. 3,855,890 to Lynch et al discloses a slitter/perforation apparatus for cutting or perforation a sheet of material, but does not disclose a sheet detection device which actuates a solenoid to cause an arm to move vertically downwardly, and engage an attached perforation wheel with sheets of material, to apply lines of perforation of selected length. The perforation roll of Lynch et al must be manually manipulated for engagement with the sheet of material for slitting or perforation.
The U.S. Pat. No. 4,641,575 to Cavagna discloses a device for embossing or creasing paper which is preferably supplied from a continuous roll. The device is intended to be fixed at a selected distance from the surface of the paper, such as toilet paper, and is not selectively movable to apply lines of perforations of controlled length on individual sheets of paper.
The U.S. Pat. No. 5,029,506 to Glendening discloses a paper perforation assembly which does crush-cut type perforation on a fixed shaft, sheet fed perforating machine. No sheet detection means, connected to control means, and connected to a solenoid for selectively actuating a perforating wheel is suggested in Glendening.
None of the prior art structures discloses the apparatus of the invention.